As a background art of the present technical field, JP-A-6-343205 (Patent Literature 1) is known. JP-A-6-343205 describes “a battery controller that determines whether communication of charging information is necessary or unnecessary and a charger controller that stops charging when it is determined that the communication of the charging information is necessary and performs the charging when it is determined that the communication is unnecessary are included in a charging apparatus of an electrical vehicle charging a vehicle-mounted battery on the basis of the charging information exchanged between a charger and the vehicle-mounted battery, to prevent erroneous transmission of information at the time of communicating the charging information between the battery and the charger,” (refer to Abstract).